The Official 2014 Fall Discussion Thread

[FallsLake]

RAH has a nice crisp forecast this weekend:

Saturday A slight chance of showers before 9am. Mostly sunny, with a high near 68. Chance of precipitation is 20%.

Saturday Night Mostly clear, with a low around 46.

Sunday Sunny, with a high near 64. **REAL FALL DAY!!!

Sunday Night Mostly clear, with a low around 45.

Monday Mostly sunny, with a high near 71.

Monday Night Partly cloudy, with a low around 53.

Tuesday Mostly sunny, with a high near 73.

Tuesday Night Partly cloudy, with a low around 56.

Wednesday Sunny, with a high near 76.

[dsaur]

Is there a reason why they trend warmer, drier, and less intense ?

This is the south. Old man winter ate some tainted moon possum pie once, and has a severe case of the ass at the south. Nearly all winter storms will thus come to naught! Do not take this personally! T

[GaWx]

This is the south. Old man winter ate some tainted moon possum pie once, and has a severe case of the ass at the south. Nearly all winter storms will thus come to naught! Do not take this personally! T

 

 I was going to say "know thy climatology" and one should be more content due to more reasonable expectations. ATL has 135 years of solid data to analyze, for example.

[Snowless in Carrollton]

I was going to say "know thy climatology" and one should be more content due to more reasonable expectations. ATL has 135 years of solid data to analyze, for example.

I hate to say that any city is due for something, but don't you think that even a city as far south as Atlanta is due a snowstorm greater than 5"? Hasn't it been 30+ years since the atl airport has had more than 5" in a single snowstorm?

[GaWx]

I hate to say that any city is due for something, but don't you think that even a city as far south as Atlanta is due a snowstorm greater than 5"? Hasn't it been 30+ years since the atl airport has had more than 5" in a single snowstorm?

 

snowstorm,

 I think KATL (south of town at the airport) is overdue for a >5" snowstorm fwiw as it has been since 3/1983 (nearly 32 years by winter's start) since 1/1992 was right at 5". However, they went from 2/1940 through 12/1981 with none (nearly 42 years) assuming you count the three day snowjam series of storms of 1/1982 as one >5" event. Also, they went from 2/1904 through 12/1935 without any (nearly 32 years) and the official startion was then further north (in or near downtown) for most of that period. (Fwiw, 1/1988, 2/1979, and 12/1917 all would have easily been >5" had it been mainly SN instead of IP. Their impact was probably much greater than a typical 5" pure snow due to the higher water content and durability of IP).

 

Edit: Savannah is also "overdue" for an official >5" snowstorm since it has been since 3/1837 (nearly 178 years). (Unofficially, some coastal areas near Savannah got nearly 5" fwiw in the amazing 12/1989 coastal).

[mackerel_sky]

Been real busy today. Is the severe threat still real with the fropa on Friday? They are canceling high school football games here already ! What are things looking like?

[jshetley]

Been real busy today. Is the severe threat still real with the fropa on Friday? They are canceling high school football games here already ! What are things looking like?

The threat of severe is still there but is looking less likely now. GSP says any severe weather will be isolated at best. The GFS still shows between .50 and 1.00 of rain on Friday, but then little if any more through the end of the run so if we miss this one it may be a while before we see anything.

[Snowless in Carrollton]

Been real busy today. Is the severe threat still real with the fropa on Friday? They are canceling high school football games here already ! What are things looking like?

That seems very silly to be cancelling high school football games 2 days ahead of time. I didn't realize this was going to be a major severe weather outbreak ?

[mackerel_sky]

That seems very silly to be cancelling high school football games 2 days ahead of time. I didn't realize this was going to be a major severe weather outbreak ?

Sorry, they are not canceling like I thought, but they are moving most high school games to Thursday , to miss the " outbreak" on Friday!

Shetley, I did just get around to reading the AFD , they did seem to downplay the event with afternoon pkg. barely mentioning severe and continuing to not put it in the HWO! The summer model blunders continue, by tomorrow evening , it will be down to a dry fropa!

[GaWx]

Regarding the potential correlation between October temp.'s & the subsequent winter wx, I just did an analysis of Atlanta going back to 1879. Here are the interesting findings, keeping in mind that it is still, of course, a good bit too early to even have a good feel for how Oct. will end up:

The longterm avg. for Oct. is near 62.7. I considered Oct.'s that were either 2+ above 62.7 or 2+ below 62.7. For these 60 Oct.'s, I then looked for DJF's that were either 2+ above normal or 2+ below normal. I found a total of 29 of these 60 Oct.'s in one of these two categories: 19 of these 29 had the same sign in DJF vs. Oct. while 10 of these 29 had the opposite sign. Of these 10, 6 were cold and 4 were warm. The 4 warm ones that had a cold winter to follow were all pretty much centered on weak to low end moderate Nino and included two of the seven coldest winters on record: 1939-40 and 1963-4. The other two were likely within the top 20 cold winters. The 6 cold Oct.'s that went into warm winters were anywhere from strong Nina to dead neutral (i.e ., no +ENSO). This all tells me that neither a cold Oct. nor a warm Oct. would favor a warm winter this time because ENSO is positive. Of course, don't forget that Nino's are biased cold in DJF in the SE US.

Looking at the 19 that kept the same sign for Oct vs DJF, there were two warm/warm that were Nino's: 1951-2 and 2004-5. There were five cold/cold that were Nino's: 1965-6, 1885-6, 1957-8, 1976-7, and 1977-8.

 

Followup to the above:

 

 As mentioned, I counted only four times since 1879 for which Atlanta had a warm Oct. (2+ above normal) that was followed by a cold winter (2+ below normal). However, all four were at or very close to the weak to moderate El Nino classification (i.e., where we appear to be heading): 1884-5 (this appears to have been borderline high end neutral positive/low end weak Nino), 1911-12, 1939-40, and 1963-4. Here were the SN/IP amounts keeping in mind the longterm 2" average:

 

-1884-5: ~11" SN/IP (2nd highest on record) including a 2-2.5" IP and a major ZR!! The DJF averaged 3 below normal (top 20 cold winter most likely)

-1911-2: 5.2" SN/IP as well as a major ZR! DJF averaged 3 below normal (top 20 cold winter most likely)

-1939-40: 8.3" SN/IP (8th highest on record)(10" downtown) & a major ZR! DJF averaged 5.5 below normal (7th coldest since 1879-80)!

-1963-4: 3.6" SN/IP along with some ZR. DJF averaged 5.7 below normal for the 6th coldest since 1879-80!

 

 For these four winters, SN/IP averaged a whopping 350% of normal (7") and 75% had a major ZR! Longterm climo for major ZR's shows only ~20% of winters have had at least one! Although this is a pretty small sample size, the 350% of S/IP climo, 75% with a major ZR, and general Nino climo tells me that a cold winter of 2014-5 following a warm Oct. of 2014 would favor a good bit greater than average wintry precip. during winter 2014-5 for even a cold winter.

 

 

 Now compare to the five El Nino's that had a cold Oct. followed by a cold DJF:

 

- 1885-6: little SN/IP and a moderate ZR; 10th coldest DJF with 4.3 below normal

- 1957-8: 2.7" SN/IP including ~1" of IP; DJF 3 below normal (likely a top 20 coldest)

- 1965-6: 0.7" SN/IP; DJF 3 below normal (likely a top 20 coldest)

- 1976-7: 1.0" SN/IP; DJF 7.6 below normal (coldest on record)

- 1977-8: 0.3" SN/IP; DJF 6.2 below normal (2nd coldest on record)

 

 So, these five Nino winters were actually a hair colder than the four weak to moderate Nino’s that followed warm Octobers. Yet, they had way less S/IP than those other four and no major ZR: only ~1" average SN/IP or only 50% of normal vs. the 350% for the four that followed warm Octobers! This tells me that a cold winter of 2014-5 following a cold Oct. of 2014 would probably favor below average wintry precip. during winter 2014-5.

 

Bottom line based on this analysis of analogs: For the best wintry precip. prospects at KATL for the winter of 2014-5, I'd actually prefer that Oct. of 2014 end up 2+ above normal at KATL rather than 2+ below normal! Of course, we'd still need to actually get the cold winter of 2014-5 to follow the warm October to maximize the chances for a snowy/icey winter.

[Wow]

0z GFS forecasting lows in the 30s for folks north of I-85 early Sunday morning.

 

[GaWx]

0z GFS forecasting lows in the 30s for folks north of I-85 early Sunday morning.

 

I'm really looking forward to this cooldown in the SE. However, (no offense intended toward John or Tony..you'll thank me later ), I sincerely now hope that the rest of October is dominated by above normal temperatures due to the warm Oct./cold winter Nino analogs I just analyzed, which suggest better wintry precip. prospects (at least in Atlanta but I suspect for much of the SE) if we end up with a cold winter after a WARM, not cold, Oct. This counterintuitive rooting for warmth in Oct. is a first for me because I'm a chilly October kind of guy.

[Snowless in Carrollton]

I'm really looking forward to this cooldown in the SE. However, (no offense intended toward John or Tony..you'll thank me later ), I sincerely now hope that the rest of October is dominated by above normal temperatures due to the warm Oct./cold winter Nino analogs I just analyzed, which suggest better wintry precip. prospects (at least in Atlanta but I suspect for much of the SE) if we end up with a cold winter after a WARM, not cold, Oct. This counterintuitive rooting for warmth in Oct. is a first for me because I'm a chilly October kind of guy.

I would be happy with an average October.

[GaWx]

I would be happy with an average October.

 

 

 To add to my other analyses and inspired by you, I just analyzed the Nino Octobers that averaged near normal and also had a cold DJF to follow. There were five of these:

 

- 1899-00: T of SN/IP; DJF 2.4 below normal

- 1904-05: 1.0" SN/IP  and two major ZR's as well as one moderate ZR; DJF 5.8 below normal (3rd coldest on record)

- 1968-69: 2.2" SN/IP; DJF 3.4 below normal (likely a top 20 coldest)

- 1969-70: 0.6" SN/IP; DJF 4.1 below normal (12th coldest on record)

- 2009-10: 5.3" SN/IP; DJF 4.4 below normal (9th coldest on record)

 

 These five cold winters averaged about as cold as each of the other two sets of cold winters. SN/IP averaged 1.8", which is near normal. One of the five had at least one major ZR, which is right at the longterm average frequency of 1+ major ZR of 20%.  So, these cold Nino winters following near normal Oct.’s were between the ones following warm Oct.'s, which were followed by the very prolific wintry precip. producers on average, and the cold Oct.'s, which had relatively paltry wintry precip. on average during the subsequent winters.

 So, in summary for Nino Oct.'s preceding cold winters, the best bet for generous amounts of wintry precip. is suggested to be a warm Oct., the 2nd best bet is a near normal Oct., and the worst bet is a colder than normal Oct.

[FallsLake]

 To add to my other analyses and inspired by you, I just analyzed the Nino Octobers that averaged near normal and also had a cold DJF to follow. There were five of these:

 

- 1899-00: T of SN/IP; DJF 2.4 below normal

- 1904-05: 1.0" SN/IP  and two major ZR's as well as one moderate ZR; DJF 5.8 below normal (3rd coldest on record)

- 1968-69: 2.2" SN/IP; DJF 3.4 below normal (likely a top 20 coldest)

- 1969-70: 0.6" SN/IP; DJF 4.1 below normal (12th coldest on record)

- 2009-10: 5.3" SN/IP; DJF 4.4 below normal (9th coldest on record)

 

 These five cold winters averaged about as cold as each of the other two sets of cold winters. SN/IP averaged 1.8", which is near normal. One of the five had at least one major ZR, which is right at the longterm average frequency of 1+ major ZR of 20%.  So, these cold Nino winters following near normal Oct.’s were between the ones following warm Oct.'s, which were followed by the very prolific wintry precip. producers on average, and the cold Oct.'s, which had relatively paltry wintry precip. on average during the subsequent winters.

 So, in summary for Nino Oct.'s preceding cold winters, the best bet for generous amounts of wintry precip. is suggested to be a warm Oct., the 2nd best bet is a near normal Oct., and the worst bet is a colder than normal Oct.

Thanks again for putting this together. So we do see some correlation to warmer Octobers and colder winters. I wonder how we could research the "big" end of October storm and warm winter theory? We can't just look at precip totals, we need to know if a large storm (nor'easter, hurricane, hybrid, etc.) effected the eastern seaboard sometime in the last 10 days of October(maybe first 5 days of November). **question for a met: would a cold October pattern be more conducive to large storm development / or a tendency for storms to direct themselves closer to the eastern seaboard? If true, then really the storm idea would go along with above analogs.

[FallsLake]

0z GFS forecasting lows in the 30s for folks north of I-85 early Sunday morning.

 

Looking at the 6z GFS, dew points will be at or below freezing for a large area of the interior SE. This is a case where if there is optimal cooling (clear calm night) we could see some temps approach the dew point; especially near the ground. It might get interesting this weekend. 

 

http://www.twisterdata.com/index.php?prog=forecast&model=GFS&grid=3&model_yyyy=2014&model_mm=10&model_dd=02&model_init_hh=06&fhour=78&parameter=DPTF&level=2&unit=M_ABOVE_GROUND&maximize=n&mode=singlemap&sounding=n&output=image&view=large&archive=false

[DaculaWeather]

4KM NAM Saturday AM. Dew point and temp. The latest runs for GFS and NAM aren't done yet on HazWx. Sunday will look even better!

 

[Cold Rain]

6z GFS builds ridging into the SE around 180 and keeps it there through the end of the run.  If that verifies, a warm October may just be in the cards.

[mackerel_sky]

I'm kind of excited about the possibilities of low 40s at some point this weekend! The models have been trending colder each day, and that's a good sign for the winter and we need this to happen for every wintry threat! A day or two ago, we were looking at lower 50s , now I think I have a real shot at 38,39 on Monday morning!! Then we go back to 80ish by end of the week, hopefully to start the October warmer up that will lead us to + 2 for the month! #GaWx

[Kory]

6z GFS builds ridging into the SE around 180 and keeps it there through the end of the run.  If that verifies, a warm October may just be in the cards.

The 00z Euro is showing to weak ridging as well toward the end of the run (not to the extent of the GFS though).  It certainly shows no cold shots in the works beyond day 7.  

[DaculaWeather]

From Mike Ventrice about October... we may get what we want!

 

https://twitter.com/MJVentrice/status/517659297233518592

 

[FallsLake]

LOL -- Wishing for a warm October.... It goes against every fabric of my being. But I'm with you guys... 

[NEGa]

its nice having the weekend trend cooler rather than warmer (although i am still always wary of the first "real" cold front of the fall season making it in),  temps have been lowering for both highs and lows with temps in the low 60s and lower 40s. i would love to see upper 30s lol

 

precip chances have also gone up, but we know how that has tended to work out lately for ne ga and the upstate

[GaWx]

Thanks again for putting this together. So we do see some correlation to warmer Octobers and colder winters.

You're welcome. Just to make sure there's no confusion, the analyzed data doesn't suggest a better chance at a cold winter if Oct. is warm vs. near normal vs. cold. Rather, as stated, it suggests that (specifically at ATL though probably also much of the interior SE, especially areas closer to storm track that brought above average wintry wx to ATL...so likely most concentrated from N and C AL through N and C GA through NW half of SC and through W and C NC including all CAD regions) there'd be better prospects for above avg. wintry precip IF the winter does actually turn out cold and Oct. is warm.

Now, granted overall Niño climo, itself, does lean toward a colder than average DJF in the SE US regardless of whether Oct. is warm, near normal, or cold. Consistent with this, a whopping 13 of the top 20 coldest winters of the 135 ATL winters since 1879-80 (all 3+ colder than avg. DJF) were pretty much in Niño territory (1884-5 is on/near border of low end weak Niño based on available data and is included). Based on overall climo averages (40 of the 135 winters were during Nino's), there would have been only 6 Nino DJF's that were 3+ colder than normal as opposed to the actual of 13.

Edit: At ATL for Nino's, alone, there were two warm DJF's that followed a warm Oct. (1951-2 & 2004-5) and four cold DJF's that followed a warm Oct. (1884-5, 1911-2, 1939-40, 1963-4). The rest of the DJF's that followed a warm Oct. were, of course, within two of normal though I think these leaned slightly colder rather than slightly warmer. For Niño's, I'll count the number of near normal DJF's following warm Oct.'s when I get a chance.

[DaculaWeather]

Temps and dew points on Sunday at 5am. GFS

 

[Cold Rain]

You're welcome. Just to make sure there's no confusion, the analyzed data doesn't suggest a better chance at a cold winter if Oct. is warm vs. near normal vs. cold. Rather, as stated, it suggests that (specifically at ATL though probably also much of the interior SE, especially areas closer to storm track that brought above average wintry wx to ATL...so likely most concentrated from N and C AL through N and C GA through NW half of SC and through W and C NC including all CAD regions) there'd be better prospects for above avg. wintry precip IF the winter does actually turn out cold and Oct. is warm.

Now, granted overall Niño climo, itself, does lean toward a colder than average DJF in the SE US regardless of whether Oct. is warm, near normal, or cold. Consistent with this, a whopping 13 of the top 20 coldest winters of the 135 ATL winters since 1879-80 (all 3+ colder than avg. DJF) were pretty much in Niño territory (1884-5 is on/near border of low end weak Niño based on available data and is included). Based on overall climo averages (40 of the 135 winters were during Nino's), there would have been only 6 Nino DJF's that were 3+ colder than normal as opposed to the actual of 13.

Edit: At ATL for Nino's, alone, there were two warm DJF's that followed a warm Oct. (1951-2 & 2004-5) and four cold DJF's that followed a warm Oct. (1884-5, 1911-2, 1939-40, 1963-4). The rest of the DJF's that followed a warm Oct. were, of course, within two of normal though I think these leaned slightly colder rather than slightly warmer. For Niño's, I'll count the number of near normal DJF's following warm Oct.'s when I get a chance.

 

Larry (or anybody), where would I find similar numbers for Raleigh?  For example, when you look at the DJF average and then the departure from average on a given year, how do you determine that?  Are those numbers readily available or do you have to calculate them based on raw data?  Same ? with SN/IP totals.  Essentially, if one were to want to do a similar analysis for RDU, what is the easiest way to access the data that would support that effort?  If it's too complicated to explain, feel free to say that.

[Snowless in Carrollton]

To add to my other analyses and inspired by you, I just analyzed the Nino Octobers that averaged near normal and also had a cold DJF to follow. There were five of these:

 

- 1899-00: T of SN/IP; DJF 2.4 below normal

- 1904-05: 1.0" SN/IP  and two major ZR's as well as one moderate ZR; DJF 5.8 below normal (3rd coldest on record)

- 1968-69: 2.2" SN/IP; DJF 3.4 below normal (likely a top 20 coldest)

- 1969-70: 0.6" SN/IP; DJF 4.1 below normal (12th coldest on record)

- 2009-10: 5.3" SN/IP; DJF 4.4 below normal (9th coldest on record)

 

 These five cold winters averaged about as cold as each of the other two sets of cold winters. SN/IP averaged 1.8", which is near normal. One of the five had at least one major ZR, which is right at the longterm average frequency of 1+ major ZR of 20%.  So, these cold Nino winters following near normal Oct.’s were between the ones following warm Oct.'s, which were followed by the very prolific wintry precip. producers on average, and the cold Oct.'s, which had relatively paltry wintry precip. on average during the subsequent winters.

 So, in summary for Nino Oct.'s preceding cold winters, the best bet for generous amounts of wintry precip. is suggested to be a warm Oct., the 2nd best bet is a near normal Oct., and the worst bet is a colder than normal Oct.

Thank you for all the research you do. It is much appreciated.

[GaWx]

For ATL for Nino's, alone, I just compiled the near normal DJF's that followed a warm Oct. and my suspicions of them leaning slightly cold were correct:

- 1900-1: -0.9 (4.4" SN/IP)

- 1918-9: +1.1 (0.4" SN/IP)

- 1941-2: -0.8 (3.8" SN/IP)

- 2002-3: -1.0 (T of SN/IP)

So, avg. SN/IP for these four near normal temperature Niño winters following warm Oct .'s was 2.2", which is 110% of normal. There were no major ZR's.

As mentioned earlier, there were two warmer than normal Niño DJF's following warm Oct.'s:

- 1951-2: +3.9 (3.9" SN/IP )

- 2004-5: +2.4 (0.5-1" SN/IP...range because record incomplete for some reason; also was a major ZR)

Also, as mentioned earlier, there were four colder than normal Niño DJF's that followed warm Oct.'s:

- 1884-5: -3.2 (~11" SN/IP & a major ZR )

- 1911-2: -2.9 (5.2" SN/IP & a major ZR )

- 1939-0: -5.5 (8.3" SN/IP & a major ZR)

- 1963-4: -5.7 (3.6" SN/IP and some ZR)

So, there have been a total of 10 of the 40 Nino's (25%) at ATL having had a warm (2+) Oct., which is close to what overall climo would predict. Of these 10, seven of the subsequent DJF temp. anomalies were in the -0.8 to -5.7 range. The other three were in the +1.1 to +3.9 range. The DJF average temp. anomaly for these 10 Nino's that had a warm Oct. was -1.3 and the average S/IP was 4.1" (205% of normal) with 40% having had a major ZR, which is twice the longterm average for all winters. As you can see by looking at the individual winter numbers, the seven cool to cold Niño winters following warm Oct's have averaged well above normal SN/IP (5.2" or 260% of normal) and ZR (even vs. overall cool to cold winter longterm averages).

Even more impressive might be that 6 of the 7 cool to cold Niño DJF's that followed warm Oct's had 190% or more of normal SN/IP!

**Edited several times**

[SnowNiner]

6z GFS builds ridging into the SE around 180 and keeps it there through the end of the run.  If that verifies, a warm October may just be in the cards.

 

Another winter season begins!!

 

All I remember is the last two times we had a big snow storm in the east, the following two winters were turrible.  One was Sandy, I forget the other one, I think it actually snowed close to Halloween or something around here.  So yeah, I'm on Board with rooting for a warm October. 

[Cold Rain]

Another winter season begins!!

All I remember is the last two times we had a big snow storm in the east, the following two winters were turrible. One was Sandy, I forget the other one, I think it actually snowed close to Halloween or something around here. So yeah, I'm on Board with rooting for a warm October.

What's up man? How's it been? You and Falls been reading from the same book. Hopefully, we can avoid any October noreasters this year!